A plant, and particularly but not exclusively a potted plant, needs a regular supply of water for healthy growth. The rate at which water must be supplied is dependent upon a number of factors, including the type and size of plant and environmental conditions. To maintain the plant in a healthy state, watering must be carried out with a frequency and in a quantity to maintain the plant's growing medium correctly moist. A sudden change in environmental conditions can lead to over or under watering. Should watering be forgotten, the growing medium could dry out causing the death of the plant.
There is, therefore, a demand for a device which can be entrusted to water a plant automatically, and various such devices have been proposed. A variety of such devices is described in the prior art, which includes WO 95/10934 and the prior art cited in the Search Report published with that document. In principle, these known devices rely upon a moisture-sensitive air valve (e.g. a porous plug), which is in communication with the growing medium, to admit air to an otherwise-sealed reservoir for controlling the dispensing of water to the medium. Whilst such devices can work well, few if any have reached the market with success, owing not least to the complexity and cost of their construction.
It is an aim of the present invention to provide self watering apparatus of improved construction.